The research portfolio of Bettstetter and his team is depicted below. We perform research on networking issues of communication systems, with major focus on mobile and wireless systems. This includes  the design of algorithms and protocols, contributions to netorking theory, modeling and simulation aspects, and system and protocol architectures. Four networking paradigms are currently in the core of the activities: self-organization, ad hoc relaying, cooperation, and exploiting mobility. 

The research methodology is theoretical, simulation-based, and experimental. Methods range from protocol engineering and system simulation over prototyping on real hardware platforms to a set of mathematical methods (mainly stochastic processes, random graph theory, and complex networks). Research is at the intersection of computer science, electrical engineering and information technology, and applied mathematics.

Of general interest are also interdisciplinary and theoretical aspects of self-organization and networked systems in general. One goal is to design technology enabling new applications that go beyond classical applications of cellular networks, WLANs, and today's Internet, such as applications in disaster management and automotive safety.

The group currently cooperates on an international level with researchers from Orange Labs, DOCOMO Euro-Labs, Soongsil University, University of Porto, TU Munich, and the University of Passau. Funding is obtained from major international companies as well as national and European funding agencies.

 

Current research activities and projects are as follows:

 

Cooperative Spatial Diversity in Ad Hoc Networks

A well-known technique to improve the robustness of wireless transmission in wireless cellular networks is spatial diversity. In this project, we apply spatial diversity to wireless multihop networks and investigate new techniques for packet transport based on this concept. Our main focus is to design and assess protocols for relay selection, packet combining, and medium access control. The two-year project is funded by Orange Labs, France.

 

Distributed Slot Synchronization in Radio Networks

We develop a distributed algorithm for slot synchronization suited for ad hoc networks. Our approach has been inspired from biology, from the synchronous flashing of fireflies. We noticed that a one-to-one transfer of the well-known firefly synchronization to wireless networks is infeasible, due to some characteristics of radio communications. We thus invented significant modifications, making the synchronization converge in multihop radio networks. Our scheme achieves high synchrony rates and a synchronization accuracy only limited by the propagation delay. The work is done in very close cooperation with DoCoMo Euro-Labs, Munich, Germany.

 

Engineering Self-Organizing Networks

Self-organizing systems consist of entities that interact with each other in simple and localized ways. Although the individual entities are simple, the system as a whole shows coordinated activity and often solves a complex task. In other words, simple interaction rules at the microscopic level may give rise to complex, adaptive, and robust behavior at the macroscopic level. While this emergent behavior can often be found in nature, there exists no straightforward method for the design of microscopic rules that achieve a desired macroscopic behavior. Existing approaches are based on try-and-error and biological inspiration. Both of them have limitations with respect to their generality. The goal of the research activities in this area is to investigate novel, generic approaches for engineering self-organizing systems, like for example evolutionary computing. In general, the methodology involves theoretical research as well as practical approaches and case studies derived from other research projects.

 

Flooding in Complex Networks

Flooding is a fundamental technique for information dissemination in several networking scenarios, such as link state advertisements in wireless multihop networks and query propagation in peer-to-peer networks. We study various flooding algorithms in different kinds of complex networks. The major goal is to take a more formal, mathematical approach than previous work, employing methods from graph theory and stochastic processes to draw conclusions for the design and parameterization of flooding algorithms. Networks under investigation include Erdös Rényi random graphs, geometric random graphs, and small world networks. Algorithms under investigation include probabilistic flooding, multipoint relaying, and flooding based on network coding. The work is done in cooperation with the the University of Porto.

 

Mobility in Sparse Wireless Networks (Acronym: SPARSE)

The goal of this project is to create a framework for modeling sparsely connected wireless networks with inhomogeneous node distributions and to design and asses protocols that exploit inherent node mobility for packet delivery is such networks. The project is partly funded by Soongsil University, Seoul, Korea within a large Korean research project.